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Abstract:

A system for driving an assembly arrangement for a motor vehicle, which
assembly arrangement having at least one auxiliary assembly and an
electric machine which is configured independently of a drive unit of the
motor vehicle. It is possible for the electric machine to be operated
both as a motor for driving the auxiliary assembly and as a generator for
generating electric power. If required, it is possible for a separate
engine which is configured as an internal combustion engine to be
connected or fastened releasably via an interface to the assembly
arrangement and to be coupled to the assembly arrangement for drive
action, in order to supply the at least one auxiliary assembly and/or the
electric machine with rotational drive moment.

Claims:

1-15. (canceled)

16. A drive system for a motor vehicle, the drive system comprising: an
assembly arrangement having at least one auxiliary assembly and an
electric machine which is configured independently of a drive unit of the
motor vehicle, the electric machine being configured for operation as a
motor for driving the at least one auxiliary assembly and as a generator
for generating electric power, and an auxiliary engine configured as an
internal combustion engine which is releasably fastened via an interface
to the assembly arrangement to provide a rotational drive moment to at
least one of the at least one auxiliary assembly and the electric
machine.

17. The drive system of claim 16, wherein the auxiliary engine comprises
an output shaft having a drive moment transmitted via one of a belt
drive, a gear mechanism or a positively locking and/or frictional
connection to the auxiliary assembly and/or the electric machine.

18. The drive system of claim 16, wherein the auxiliary engine comprises
at least one of a fuel system, a control system, an air supply system, an
exhaust gas system and an connecting interface configured to permit
coupling of the auxiliary engine to corresponding components of the motor
vehicle.

19. The drive system of claim 16, wherein the auxiliary engine comprises
a dedicated fuel tank, the auxiliary engine being configured for
operation independently of the assembly arrangement.

20. The drive system of claim 16, further comprising a switchable
coupling device configured to selective decouple at least one of the
auxiliary assembly and the electric machine from a connection for drive
action to the auxiliary engine.

21. The drive system of claim 20, wherein the switchable coupling device
comprises a magnetic coupling.

22. The drive system of claim 16, wherein the interface comprises a
plurality of centering apparatuses configured to mount the auxiliary
engine.

23. The drive system of claim 16, wherein the interface is configured to
permit fastening of the auxiliary engine to one of the electric machine
and the auxiliary assembly.

24. The drive system of claim 16, wherein the interface comprises a
fastening apparatus having a quick action closure system with a toggle
lever mechanism.

25. The drive system of claim 16, wherein the assembly arrangement
comprises a single piece structure element configured to support the
auxiliary assembly and the electric machine.

26. The drive system of claim 16, wherein the auxiliary engine comprises
a starter device for starting the auxiliary engine, the starter device
being configured for operation independently of the electric machine.

27. The drive system of claim 16, wherein the auxiliary engine comprises
at least one of a heat and sound insulating housing.

28. A motor vehicle comprising: an assembly arrangement having at least
one auxiliary assembly and an electric machine which is configured
independently of a drive unit of the motor vehicle, the electric machine
being configured for operation as a motor for driving the at least one
auxiliary assembly and as a generator for generating electric power, an
auxiliary engine configured as an internal combustion engine which is
releasably fastened via an interface to the assembly arrangement to
provide rotational drive moment to at least one of the at least one
auxiliary assembly and the electric machine.

31. A method for operating an assembly arrangement of a motor vehicle,
the method comprising: providing an assembly arrangement having at least
one auxiliary assembly and an electric machine which is configured
independently of a drive unit of the motor vehicle, wherein the electric
machine is configured for operation as a motor for driving the at least
one auxiliary assembly and as a generator for generating electric power;
and then providing an auxiliary engine configured as an internal
combustion engine which is releasably fastened via an interface to the
assembly arrangement to provide rotational drive moment to at least one
of the at least one auxiliary assembly and the electric machine.

32. The method of claim 31, further comprising operationally fastening
the auxiliary engine to the assembly arrangement if at least one of the
drive unit does not supply any drive moment to operate the assembly
arrangement and a charge state of an energy storage which is assigned to
the electric machine is less than a predetermined value.

33. The motor vehicle of claim 31, further comprising operationally
detaching the auxiliary engine from the assembly arrangement and storing
the auxiliary engine separately therefrom if at least one of the drive
unit supplies drive moment sufficient to operate the assembly arrangement
and the charge state of the energy storage which is assigned to the
electric machine is greater than a predetermined value.

34. The method as claimed in claim 31, further comprising selectively
decoupling at least one of the auxiliary assembly and the electric
machine from the auxiliary engine via a coupling device in order to
distribute the drive moment which is applied by the auxiliary engine in
accordance with requirements.

35. The method of claim 31, wherein the motor vehicle comprises one of a
hybrid motor vehicle and an electric motor vehicle.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a National Stage Application of PCT
International Application No. PCT/EP2010/059511 (filed on Jul. 2, 2010),
under 35 U.S.C. §371, which claims priority to U.S. Provisional
Patent Application No. 61/222,958 (filed on Jul. 3, 2009), which are each
hereby incorporated by reference in their respective entireties.

FIELD OF THE INVENTION

[0002] Embodiments of the present invention relates to a system for
driving an assembly arrangement for a motor vehicle.

BACKGROUND OF THE INVENTION

[0003] In a conventional vehicle having an internal combustion engine for
providing drive torque for driving the vehicle forward, as a rule
auxiliary assemblies of the vehicle, such as air conditioning
compressors, water and fuel pumps, are driven directly by the internal
combustion engine, i.e., are supplied with a torque. In electric and
hybrid vehicles, a problem occurs such that when the vehicle is at a
standstill, no drive moment which might drive the auxiliary assemblies is
provided by the electric motor which acts as drive unit.

[0004] In order to solve this problem, instead of rotationally driven
auxiliary assemblies, electrically operated auxiliary assemblies can be
used which take the energy which is necessary for their operation from a
battery of the vehicle. Electrically operated auxiliary assemblies of
this type, however, are considerably more expensive than conventional
auxiliary assemblies with rotary drive.

SUMMARY OF THE INVENTION

[0005] It is therefore an object of the present invention to provide a
system for driving an assembly arrangement, which system operates
reliably and efficiently and which system is also at the same time
inexpensive to produce.

[0006] This object may be achieved by a system for driving an assembly
arrangement for a motor vehicle, which assembly arrangement including at
least one of the following: at least one auxiliary assembly and an
electric machine which is configured independently of a drive unit of the
motor vehicle. It is possible, therefore, for the electric machine to be
operated both as a motor for driving the auxiliary assembly and as a
generator for generating electric power. It is also possible, if
required, for a separate auxiliary engine which is configured as an
internal combustion engine to be fastened releasably via an interface to
the assembly arrangement and to be coupled to the assembly arrangement
for drive action, in order to supply the auxiliary assembly and/or the
electric machine with rotational drive moment.

[0007] In accordance with the invention, the system includes at least one
of the following: at least one auxiliary assembly and an electric machine
which is configured independently of a drive unit of the motor vehicle.
The electric machine can be operated both as a motor for driving the
auxiliary assembly and as a generator for generating electric power. It
is possible, if required, for a separate auxiliary engine which is
configured as an internal combustion engine to be fastened releasably via
an interface to the assembly arrangement and to be coupled to the
assembly arrangement for drive action, in order to supply the at least
one auxiliary assembly and/or the electric machine with rotational drive
moment.

[0008] In essence, the system includes one or more auxiliary assemblies,
an electric machine which generates a drive moment if electric energy is
applied or vice versa, and an auxiliary engine. If the electric machine
is operated as a motor, it drives the at least one auxiliary assembly by
providing a rotational drive moment. The latter is transmitted directly
or indirectly from the electric machine to the auxiliary assembly which
can therefore be configured as a conventional auxiliary assembly. Not
every auxiliary assembly, therefore, has to be supplied with electric
power to ensure its functional capability. Electric power has to be
provided only to the electric machine which is configured separately from
a motor which is provided for driving the vehicle forward.

[0009] If required, the auxiliary engine is a part of the system but is of
separate configuration. Moreover, for example, the auxiliary engine can
be mounted at any desired location in the vehicle in a manner which
permits decoupling or otherwise detachment from the assembly arrangement
when not in use is coupled to the assembly arrangement, in order to make
the latter independent of an electric supply or at least to reduce the
removal of electric power by the assembly arrangement from an energy
storage of the motor vehicle. For this purpose, the auxiliary engine is
attached via a suitably designed interface to the assembly arrangement
and is also coupled to the latter for drive action. The coupling for
drive action can take place directly between the auxiliary engine and the
at least one auxiliary assembly. As an alternative or in addition, the
electric machine can also be driven by the auxiliary engine.

[0010] The interface makes possible rapid and simple coupling of the
auxiliary engine to the assembly arrangement. Those parts of the
interface which are assigned to the auxiliary engine and the assembly
arrangement are preferably configured in such a way that the coupling can
also be performed by a user of the motor vehicle who has not been trained
specially.

[0011] The configuration of the auxiliary engine as an internal combustion
engine makes it possible to operate the at least one auxiliary assembly
without problems even with limited electric resources. Since the electric
machine can also be operated as a generator, the auxiliary engine can
additionally also be used to charge the energy storage. The auxiliary
engine is coupled to the assembly arrangement, for example, when the
energy storage of the vehicle is empty and a certain distance has to be
overcome to a charging station, where the energy storage can be charged.
After the energy storage has been recharged, the auxiliary engine can be
removed. The system can, therefore, be adapted in a simple way to the
respectively prevailing conditions.

[0012] In accordance with one advantageous embodiment of the invention, a
drive moment of an output shaft of the auxiliary engine can be
transmitted via a belt drive, a gear mechanism or a positively locking
and/or frictional connection to the auxiliary assembly and/or the
electric machine.

[0013] The auxiliary engine can have a connecting interface which is
configured in such a way that a coupling of a fuel system, a control
system, an air supply system and/or an exhaust gas system of the
auxiliary engine to corresponding components of the motor vehicle can be
produced. In essence, certain components of the auxiliary engine can
access resources of the motor vehicle via the connecting interface. For
example, in a hybrid vehicle, the auxiliary engine can be connected to
the fuel system of the vehicle, which fuel system is present in any case,
in order to supply the auxiliary engine with fuel. In the case of a
failure of the primary internal combustion engine of the hybrid vehicle
and an (almost) empty battery, the auxiliary engine can then be operated
to supply electric power at least for operating the auxiliary assemblies
and/or for emergency operation of an electric drive motor of the vehicle
and/or to charge the energy storage of the vehicle.

[0014] In principle, the auxiliary engine can also be a module which can
be operated independently of the assembly arrangement and includes, in
particular, a dedicated fuel tank--which does not rule out the presence
of a connecting interface of the above-described type. A modular design
of the auxiliary engine facilitates the coupling as required of the
auxiliary engine to the assembly arrangement. An auxiliary engine of
modular design of this type can in principle be operated independently of
other components of the vehicle and can therefore also be used in
non-vehicular fields of application (for example, as a generator or drive
unit in the leisure, hobby and/or garden sector).

[0015] In particular, the auxiliary assembly and/or the electric machine
can be decoupled selectively from the connection for drive action to the
auxiliary engine via a switchable coupling device, in particular, a
magnetic coupling. As a result, depending on the respectively prevailing
situation, individual auxiliary assemblies or a plurality of auxiliary
assemblies and/or the electric machine can be coupled or decoupled as
required, in order to adapt the power requirement of the assembly
arrangement on a situation by situation basis to the power output of the
auxiliary engine. The power which is generated by the auxiliary engine
can be "channeled" as a result. In particular, auxiliary assemblies with
a particularly high power requirement and/or auxiliary assemblies which
fulfill merely a comfort function are decoupled in certain situations.

[0016] In order to facilitate positionally accurate mounting of the
auxiliary engine, it can be provided that the interface includes
centering apparatuses for the fastening and the coupling for drive action
of the auxiliary engine. Furthermore, the interface can be configured in
such a way that the auxiliary engine can be fastened to the electric
machine and/or the auxiliary assembly. If the assembly arrangement
includes a single piece structure element which supports the auxiliary
assembly and the electric machine, the auxiliary engine can also be
fastened to the structure element.

[0017] Mounting of the auxiliary engine is facilitated if the interface
has a fastening apparatus which includes a quick action closure system,
in particular, with a toggle lever mechanism. It is particularly
advantageous if the fastening apparatus can be operated without a tool;
it is to be ensured that the fastening can be carried out reliably,
simply and quickly.

[0018] The auxiliary engine can include a starter device for starting the
engine, which starter device can preferably be operated independently of
the electric machine. A starter device can include, for example, a cable
pull mechanism. It is also possible in principle that a starter device of
this type is provided as a redundant starting option for the auxiliary
engine, to which recourse is made only when the electric machine is not
capable of performing starting of the auxiliary engine. This can occur,
for example because the energy storage which supplies it with electric
power is empty. Starting of the auxiliary engine by the electric machine
can take place, for example, via a control system of the assembly
arrangement. The control system can additionally be configured in such a
way that starting of the auxiliary engine with the aid of the starter
device is detected, in order to take this information into consideration
during the actuation of the further components of the assembly
arrangement.

[0019] In accordance with one advantageous embodiment, the auxiliary
engine has a heat and/or sound insulating housing. The heat insulation of
the housing makes it possible to remove the auxiliary engine after its
operation without a relatively long waiting time for cooling when its
drive power is no longer required. The sound insulation proves to be
advantageous, in particular, if the auxiliary engine is used in
non-vehicular fields of application.

[0020] Embodiments of the invention further relates to a motor vehicle, in
particular a hybrid or electric vehicle having a system in accordance
with at least one of the above-described embodiments.

[0021] Embodiments of the invention also relates to a method for operating
an assembly arrangement for a motor vehicle, in particular, a hybrid or
electric vehicle, which assembly arrangement includes at least one of the
following: at least one auxiliary assembly and an electric machine which
is configured independently of a drive unit of the motor vehicle. It is
possible for the electric machine to be operated both as a motor for
driving the auxiliary assembly and as a generator for generating electric
power. If required, a separate auxiliary engine which is configured as an
internal combustion engine is fastened to the assembly arrangement and is
connected to it for drive action, in order to supply the at least one
auxiliary assembly and/or the electric machine with rotational drive
element.

[0022] In accordance with one embodiment of the method, the auxiliary
engine is fastened to the assembly arrangement and is connected for drive
action to the latter if the drive unit does not supply any drive moment
to operate the assembly arrangement and/or a charge state of an energy
storage which is assigned to the electric machine has dropped below a
predefined threshold value. The auxiliary engine is detached from the
assembly arrangement and is stored separately from it if the drive unit
supplies sufficient drive moment to operate the assembly arrangement
and/or a charge state of the energy storage which is assigned to the
electric machine has risen above a predefined threshold value.

[0023] In accordance with a further embodiment, the auxiliary assembly
and/or the electric machine are/is decoupled selectively from the supply
with rotational drive moment via a coupling device, in order to
distribute the drive moment which is applied by the auxiliary engine in
accordance with requirements.

[0024] Further embodiments of the present invention are specified in the
description, the drawings and the subclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention is described in more detail in the enclosed figures
and drawings, which present an implementation example. The drawings
demonstrate:

[0026]FIG. 1 diagrammatically illustrates a system for driving an
assembly arrangement of a motor vehicle in accordance with an embodiment
of the invention.

[0027]FIG. 2 diagrammatically illustrates a system for driving an
assembly arrangement of a motor vehicle in accordance with another
embodiment of the invention.

[0028] FIGS. 3A and B diagrammatically illustrates a system for driving an
assembly arrangement of a motor vehicle in accordance with a further
embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0029]FIG. 1 diagrammatically shows the components of a drive of a motor
vehicle. The motor vehicle is an electric vehicle which is driven by an
electric motor 10. The electric motor supplies drive moment to at least
one of the front wheels 12 and the rear wheels 14 of the vehicle.

[0030] The electric motor 10 is supplied with current by a battery 16. The
direct current which is supplied by the battery 16 is converted in a
DC/AC converter 18 into alternating current which is necessary for the
operation of the electric motor 10.

[0031] Furthermore, the battery 16 is connected to an assembly arrangement
20 which includes a plurality of auxiliary assemblies 22a to 22e. An
auxiliary assembly is to be understood as, for example, an air
conditioning compressor, a water pump such as an electric water pump, a
vacuum pump such as an electric vacuum pump, a pump for a steering system
such as an electric pump, or the like. The auxiliary assemblies 22a to
22e are not drive-connected mechanically or otherwise in mechanical
communication with the electric motor 10, i.e., they are not supplied
with rotational drive moment by the electric motor 10. As can be gathered
from the diagrammatic illustration of FIG. 1, the auxiliary assemblies
22a to 22e are also not connected electrically or otherwise in electric
communication with the battery 16. This is also not necessary, since the
auxiliary assemblies 22a to 22e are supplied with rotational drive moment
by an additional assembly 24. Meaning, auxiliary assemblies 22a to 22e
can be conventional-types which are also installed in motor vehicles of
conventional type.

[0032] The additional assembly 24 can be, for example, an electric machine
which is configured to act both as an electric motor and as a generator.
Like the electric motor 10, it is connected or otherwise in communication
to the battery 16 via a second DC/AC converter 18'.

[0033] In essence, operation of the assembly arrangement 20 is ensured by
the additional assembly 24 which is a separate component from the
electric motor 10. The coupling for drive action of the additional
assembly 24 to the auxiliary assemblies 22a to 22e can be produced in any
desired way, for example, by one or more belt or chain drives and/or
gearwheel connections.

[0034] In the present refinement of the assembly arrangement 20, the
auxiliary assembly 22e is a generator which supplies current for a 12V
power supply 26 of the vehicle. Although it is possible in principle to
take the electric power for the 12V power supply 26 from the battery 16,
a comparatively expensive DC/DC converter would be necessary for this
purpose. Although power losses arise as a result of the use of a
conventional generator in comparison with a use of a DC/DC converter,
they are compensated for again by cost advantages.

[0035] The auxiliary assemblies 22a to 22e can be decoupled selectively
from the additional assembly 24 in each case by magnetic couplings which
are assigned to them. In this way, it is possible to feed the rotational
drive moment which is generated by the additional assembly 24 to those
components of the assembly arrangement 20 which are most important in the
respective situation in a targeted manner.

[0036] If a charge state of the battery 16 is so low that operation of the
assembly arrangement 20 to the required extent is no longer ensured, an
auxiliary engine 30 is coupled to or otherwise in communication with the
assembly arrangement 20. The auxiliary engine 30 is configured to supply
the rotational drive moment which is necessary for operation of the
assembly arrangement 20 and/or to generate electric power by use of the
additional assembly 24 as a generator, which electric power is fed to the
battery 16. The auxiliary engine 30, therefore, has two functions which
it fulfills alternately or simultaneously: (1) generation of electric
power to charge the battery 16; and (2) operation of the auxiliary
assemblies 22a to 22e. If the main attention is focused on the charge of
the battery 16, the auxiliary assemblies 22a to 22e cart be decoupled
selectively, as has already been described briefly above, in order that
as much drive moment of the auxiliary engine 30 as possible is converted
into electric power by the additional assembly 24. If this aspect is only
of subordinate significance, the additional assembly 24 can be decoupled
from the rest of the assembly arrangement 20 and/or the auxiliary engine
30, given suitable coupling of the auxiliary engine 30 to the auxiliary
assemblies 22a to 22e.

[0037] In accordance with the present embodiment, the auxiliary engine 30
is connected to or otherwise in communication with the additional
assembly 24, and therefore, drives the latter directly. The auxiliary
engine 30 includes an air intake system 30a, an exhaust gas system 30b
which is equipped depending on the requirement with exhaust gas treatment
devices, and a fuel tank 30c. The connection for drive action of the
auxiliary engine 30 to the additional assembly 24 takes place via a
coupling element 30d which produces, for example, a positively locking or
frictional coupling between a drive shaft of the auxiliary engine 30 and
a shaft of the additional assembly 24. Alternative coupling options are
likewise conceivable, such as belt or chain connections or a coupling via
gearwheels.

[0038] The auxiliary engine 30 can also be operated independently of the
assembly arrangement 20 and can be used, for example, in the hobby and/or
garden sector for operating different types of devices or as a generator.
In contrast to the assembly arrangement 20, it is not installed
permanently in the motor vehicle. If there is no demand for its drive
power, it can be stored at a suitable location for portable use, for
example, in the trunk of the vehicle.

[0039] The connection between the auxiliary engine 30 and the additional
assembly 24 should be configured for being produced quickly and simply,
with the result that a person who is not trained expertly can also
install the auxiliary engine 30. To this end, the auxiliary engine 30 and
the additional assembly 24 have complementary segments of an interface
which automatically ensure correct mounting of the auxiliary engine 30,
for example, with the aid of suitable centering pins and/or guiding aids.
It is preferably possible to fasten the auxiliary engine without tools.
For this purpose, in particular, quick action clamping systems with a
toggle lever mechanism are provided.

[0040] The interface for connecting the auxiliary engine 30 to the
assembly arrangement is preferably readily accessible, in order to
simplify the mounting of the units. The rotational axes of the auxiliary
engine 30 and the auxiliary assemblies 22a to 22e and of the additional
assembly 20 do not necessarily have to be arranged parallel to one
another, if the available installation space does not make an arrangement
of this type possible

[0041]FIG. 2 illustrates an assembly arrangement 20', the components of
which are arranged in a spatially somewhat different form, when compared
to the assembly arrangement 20 of FIG. 1. Moreover, it can be seen that
the individual auxiliary assemblies 22a to 22e can be decoupled from the
additional assembly 24 by coupling units 28, With the exception of the
auxiliary assembly 22b, a water pump in the present embodiment, the
auxiliary assemblies 22a to 22e are connected to or otherwise in
communication with a control unit 32 which is in turn connected to or
otherwise in communication with a CAN bus 34 of the vehicle. The
converter 18' and an auxiliary engine control unit 36 are also actuated
via the control unit 32. The control unit 32, the converter 18' and the
auxiliary engine control unit 36 together form an assembly arrangement
controller 38.

[0042] In addition to the components which are illustrated in FIG. 1, the
auxiliary engine has a fan 30e which is configured to cool the auxiliary
engine 30 if required, and thus, also to be able to maintain longer
"emergency operation" of the assembly arrangement 20'. An extension of
the maximum operating duration of the auxiliary engine 30 without
intervention by the user is possible, in particular, when the fuel tank
30c and/or the exhaust gas system 30b are/is connected to corresponding
systems of the vehicle if present. Cooling of the auxiliary engine 30 can
also be associated with a cooling system of the vehicle.

[0043] FIGS. 3A and 3B illustrate a further embodiment of an assembly
arrangement 20'' in a plan view (FIG. 3A) and in a side view (FIG. 31B).
Like the additional assembly 24, the individual auxiliary assemblies,
namely, a power steering pump 22a, a water pump 22b, an air conditioning
compressor 22c, a vacuum pump 22d and a generator 22e, are fastened or
connected to a crossmember 40 which is installed fixedly at a suitable
location of the vehicle, in particular in the region of the drive. The
auxiliary assemblies 22a to 22e are connected for drive action to the
additional assembly 24 via a belt 42. In order to constantly ensure a
suitable tension of the belt 42, belt tensioners 44 are provided.

[0044] In contrast to the systems described using FIGS. 1 and 2, the
auxiliary engine 30 is not fastened or connected to the additional
assembly 24 here. The fastening can take place, for example, to one of
the auxiliary assemblies. In FIGS. 3A and 3B, the fastening takes place
by way of example to the vacuum pump 22d, since this results in an
overall particularly compact design of the system which includes assembly
arrangement 20'' and auxiliary engine 30. The coupling for drive action
of the auxiliary engine 30 to the additional assembly 24 takes place via
a second belt 42' which is arranged in a plane parallel to the belt 42.
Although the non-coaxial arrangement of the drive shaft of the auxiliary
engine 30 and the additional assembly 24 requires the use and
installation of an additional coupling element, namely the belt 42', this
additional mounting is simple to bring about and the coupling element 30d
illustrated in FIG. 1 is dispensed with. Moreover, the system has a
reduced installation space requirement in the axial direction of the
components. In addition, in accordance with one special embodiment, the
transmission ratio between the auxiliary engine 30 and the additional
assembly 24 can be adapted to the respective requirements of the
components by a suitable selection of the belt pulley diameter.

[0045] The configuration of the assembly arrangement 20'' makes it
possible in a simple way to decouple the additional assembly 24
functionally (for example, by a coupling unit on its drive shaft), in
order to drive only the auxiliary assemblies 22a to 22e by the auxiliary
engine 30 in certain situations.

[0046] The auxiliary engine 30 is preferably enclosed, in order that sound
insulation and thermal insulation are ensured. The thermal insulation
makes it possible to dismantle the auxiliary engine 30 even in a "warm"
state. Moreover, the enclosure can be configured in such a way that an
air flow over the engine 30 is formed as advantageously as possible, in
order to cool said engine 30 efficiently.

[0047] Although embodiments have been described herein, it should be
understood that numerous other modifications and embodiments can be
devised by those skilled in the art that will fall within the spirit and
scope of the principles of this disclosure. More particularly, various
variations and modifications are possible in the component parts and/or
arrangements of the subject combination arrangement within the scope of
the disclosure, the drawings and the appended claims. In addition to
variations and modifications in the component parts and/or arrangements,
alternative uses will also be apparent to those skilled in the art.